The need to recycle aluminum cans over the past ten years has been responsible for a recycling infrastructure in which a variety of considerations need to be met. In some states, a mandatory fee is charged to the consumer in conjunction with the sale of the can which can be refunded when the can is turned back to the retailer. In other states, the recycling function is governed solely by the weight of the returned cans and the price for scrap aluminum. Other mechanisms for the return of aluminum cans include machines in which a can is deposited and within which the bar code is read to determine both the number and type of cans turned in before automatically paying the customer.
In instances where cans are purchased because of their weight, the crushing of the can will assist in having a storage mass of considerably less volume for a given weight. Because of this advantage, a myriad of can crushing devices have found their way onto the market. Of these, some are safer than others. Some can crushers are industrial strength, massively powered and intended to perform bulk crushing of a high volume of cans. This type of application is ideal for situations where the cans may be rapidly and continuously fed without much starting and stopping which would be present at the point of sale. After crushing, and particularly with the larger machines, the identity of the can may be undiscernible. In fact, where the crushing is particularly violent, the portion of the can having writing and the end portions may be partially shredded.
At the other end of the spectrum is the manual crusher. This item is usually hand fed a single can at a time, and may require both arms to crush the can. Usually a lever is employed to give mechanical advantage. The can's lid is usually laterally partially crushed along with the body. The volume reduction will usually not be as great as that achievable with the large electrically powered machines. In both instances, however, the ends of the cans are deformed, which may not present a problem where the cans are sold based upon weight.
In the case of pre-sale crushing of cans, it may be desirable to carefully crush the cans so as to leave the ends intact for several reasons. First, the ends are usually made of thicker material than the can's side. If a choice between two materials is to be made with regard to which will be folded, the folding of the thicker material will yield a larger internal airspace, for a given amount of crushing energy.
Second, the end portions may carry information, impressed at the time of the can's formation, relating to the can's refund amount. More specifically the inforation may include the state within the United States, or country with which the can was designated at the time the can was formed. Some states have a higher refund amount than other states, and typically the states with the higher refund amounts will also carry a state identification which has to match with the locale of the facility at which it is being returned, usually a grocery store. This problem can be especially keen in communities located near state borders where the cross-flow of cans from one jurisdiction to another is very likely.
The third problem relates back to the problem of identification of the type of can. If a can is crushed, it will likely be impossible to tell the size of the can, unless the volume label is present and can be read. Most crushing, even where the crushed can product is generally of a uniform type, leaves the can in a condition where it is impossible to readily ascertain its volume.
A fourth problem relates to the energy for crushing cans. In most crusher configurations, the crushing is a partial crushing, or where an attempt is made to insure that the can is identifiable, there is usually a tradeoff between identifiability of the can and the amount of crushing applied. In the case of human powered, or manual can crushers, the degree to which the cans are crushed is depend upon the playoff between two factors, simplicity and applied power. Since the human power input from a simple machine is limited, a simple lever type machine will be limited in the amount of crushing power which the can may receive. Where more power is sought to be applied to the can, further mechanics can be employed. These further mechanics increase the complexity of the can crusher, and the power which can be applied to the can.
A major consideration is can crusher safety. If the crushing chamber can be accessed by the human limbs and digits, the potential for serious injury will be present. Where manual crushers are configured to increase the application of power to the crushing chamber, and such chamber is accessible to the fingers and hands, the potential for injury is high.
A further problem with manual crushers is the time and energy application of power to the crushing process. Most manual crushers require the operator to perform a two-step process. In one step, requiring little or no energy, the can is loaded into the crusher. In the second step, human power is applied to crushing chamber. The energy capacity of the human during the loading step is under utilized. Further, most manual crushers are hand and arm powered, rather than foot and leg powered. A larger supply of power can be derived from the latter than the former.
One electrically powered attempt at foldably crushing cans is described in U.S. Pat. No. 4,291,618 to Warren R. Heiser and entitled "Method and Apparatus for Folding and Crushing Empty Cylindrical Cans." The configuration there involved a zig-zag hopper feeding a chamber having a complex ram set in which a center ram operated in coordination with a following central ram. A complex set of gears and levers processes each can with a two step motion in the chamber. A set of fingers are used to hold the can during the dual action crushing process.
In this configuration, however, the can exit chute is not long enough nor narrow enough to preclude an operator from inserting fingers and hands into the chute. Such an accident may occur if a can becomes trapped in the chute or upon the complex fingers which hold the can in place. In the above mentioned machine there is no easy, safe way to clear the crushing chamber and exit chute. This is particularly dangerous in an electric powered device, and virtually precludes the possibility of operation by children and young adults due to the danger potential.